PVC Inch and Metric Industry Standard

Industrial PVC Pipe and Fittings are available in both inch & metric industry standards and conform to all relevant British and DIN specifications. PVC is a generic term used to describe the pipe, although more correctly it should be termed UPVC or PVCU.

Wide Range of Industrial Applications

PVC Pipe and Fittings are suited to many applications. They are probably the most widely used plastic pipe systems in industrial pressure applications and are found in the water treatment, swimming pool, cooling, heating, chemical and process industries to name but a few.

Specifications

Plastic Pipe and fittings can be subdivided onto two main categories:

Imperial

These and fittings are typically found in North America and the UK and use a measurement and fittings, denoted in inches, which is based on the "approximate bore" (also referred to as the "nominal bore") of the pipe. For example a 2" pipe will have a "nominal bore" of 2 inches. The likelihood is that nothing on the pipe will measure exactly 2 inches!

Here's why; The outside diameter of a plastic pipe is the one which is 100% consistent, no matter what the pressure rating of the pipe. The wall thickness changes with pressure rating (thicker for high pressure and thinner for lower pressure), but the outside diameter always measures the same. This is so that no matter what pressure of pipe you have, it will always fit every fitting, valve etc., as it is the outside of the pipe that slots into the fitting's socket.

This left the original plastic pipe design engineers with a problem. From their perspective, pipe and fittings were all to do with the inside diameter of the pipe, as this governed the flow and head-loss characteristics. As a result, they set out a range of standards which ensured that if a pipework engineer was doing his calculations, a 2" pipe would have a bore of about 2" , which would make his calculations easier. What that meant, was that the outside diameter of a 2" pipe would be quite a bit larger, as it had to be ensured that even with the highest pressure rating of pipe (with the thickest wall) that the inside diameter was still in the region of 2".

As a result, the standard outside diameter of 2" PVC pipe, ended up at 60.3mm, which is 2.37". Rather confusingly, this then meant that 1 1/2" pipe, like all imperial pipe, also has a larger standard outside diameter than 1 1/2" , and this measurement ended up at 48.3mm (or 1.9 inches) - which is almost 2"!

Metric

The metric plastic pipe and fittings was developed much later than the imperial pipe and fittings (above). It was also developed, some would say, with a bit more sense. Like the imperial and fittings, the controlled diameter is the outside diameter of the pipe and remains consistent throughout different pressure ratings. However, unlike the imperial and fittings, the outside diameter of the pipe is the stated diameter. So; a 63mm pipe will always measure 63mm on the outside diameter.